nelson



(No Model.)

l Zi Patented 0011.22, 1895.

P. w. NELSON. BIT.

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UNITED STATES PATENT err-cs.

FRANK W. NELSON, OF CHICAGO, ILLINOIS, ASSIGN-OR 0F ONE-THIRD TO LYM-ANB. COE, (9F SAME PLACE.

BIT.

SPECIFICATION forming apart of Letters Patent No.;54.8,38'5, datedOctober 22, 1895.

Application filed I (1118 8, 1895. seen No. 552,115. (No model.)

To all whom it may-concern.-

Be it knownthat I, 'F'RANK NELSON, a citizenof the "United States,residing at Ohicago, in the county of Cook and State of Illinois, haveinvented a new and useful Improvement in Bits, of which the following isaspecification.

My invention relates to animprovementin the tool known as a bit, andwhich involves as its parts a stem'adapted to be inserted at one endinto and fastened in a suitable holder or handle and provided'at itsopposite pointed end with a rotary cutter.

More particularly stated, my invention relates, primarily, to animprovement in the class of bits having the cutter portion inthe form ofa readily removable and replaceable attachment on the stem to affordwhat may properly be termed a multiple tool possessing the attribute ofeconomy in the matter of original cost and in that of its use byadapting the same stem to be used for outters of many different sizes orvarieties.

My object is to provide an improved construction of the cutter-head ofabit,'and particularly, though not exclusively, of a bit having aremovable'and replaceable cutter-head; and my further object is toprovide a generally-improved construction of interchangeable bit.

Referring to the accompanying drawings, Figure 1 shows my improved bitby a viewin elevation. Fig. 2 is an enlarged broken sectional view ofthe same with the gage omitted; Fig. 3, a view in elevation of thegage-holder; Fig. at, an end view of one of the attachable and separablecutter-heads; and Fig. '5, a view of the same in elevation,showing amodificatlon.

A is the stem, provided at one end with a head r, adapted to be insertedinto a holder or handle, (not shown,) and which stem should be ofuniform or substantially uniform diameter throughout from the head to acircumferential shoulder q, provided near its opposite end, and fromwhich it tapers by preference only to a point as, whence it may beuniform in diameter to the point t, which should be screw-threaded. Onthe stem is provided a suitable spring-catch device or look B, adesirable construction of which is that illustrated, involving a recess10, formed in the stem and undercut *in its upper end, while from thelower end of "the recess, which may be straight, extends a slot 13"lengthwise of the stem to the shoulder q, toward which its depthincreases. The catch is formed of a bar or strip of sprin'gy metal,provided at one end with ahead 0, conforming inshape to that of therecess p, which it enters, the bar be ing provided toward its lower endwith a button 0" and at its lower end with a stud or key 0 projectingata right angle, and the extent of the projection of which should not begreater than the extent of its play in the slot 19', in order that bydepressing'the bar at its button 0 the outer surface of the stud may bebrought flush with thecircumferential surface of the stem A.

O is the tubular cutter-head, adapted at will to be applied to andremoved from the stern A. It is of the general somewhat cylindrical formillustrated,the longitudinal opening through it conforming to theexternal contour of the stem from'apoint above the shoulder q to ornearly to the point t, whereby it contains an internalshoulder q to meetthe shoulder on the stem. In the body of the head '0 is formed alongitudinal slot 0 at a point to coincide with the key 0 when the headis adjusted on the stem to a point at whichthe shoulders q and q meet,the adjustment being effected by depressing the catch-bar at its button0' and slipping upon the stem from its point end a head 0 till stoppedby abutment of the shoulders, when on releasing the button the key 0will spring into the-slot 0 and thus engage the cutterhead to hold it inplace. Of course the key 0 must not project beyond the external sur-'face of the cutter-head, so that the depth of the slot 0 inthe directiondiametrically of the cutter should at least equal the width in thecorresponding direction of the stud. In a cutter-head of the larger sizethe thickness of metal of its body portion may be suflicient to have theslot 0 formed therein, as shown in Fig. 5,.and the spiral rib it aboutthe body portion may then be narrow, as represented in that figure; butin the smaller sizes of the head, the metal of the body portion notbeing thick enough for a slot 0 as deep as the width of the key 0 as itis required to be for all of the various sizes of interchangeable headsfor the tool, the spiral rib n should be accordingly wider, asrepresented in Fig. 1, in order that the slot 0 may be formed throughthe additional thickness of metal it affords. The spiral rib starts attheupper end of the head 0 and terminates at the lower end thereof in aknife-edge v, extending from a point at or nearly in line withthelongitudinal center of the head to the outer circumference thereof,where, moreover, behind the plane of said cutting-edge there is provideda downward-extending cutting lip or point to. Close to the centralopening through the head 0 on its lower end I provide another andnarrower cutting-edge o and behind and adjacent to it on the externalside of the arc of which it forms the terminus (andwhich is concentricwith the are on which the point to is pro vided) a downward-extendingcutting lip or point w. Thus thehead is provided on'its lower end withan innercutter-edge and inner cutter-point and an outer cutter-edge andouter cutter-point, whereby the cutting action is facilitated, and theshavings which are cut must be sufficiently narrow to pass freely alongthe spiral afforded by the spiral rib u, and thus avoid clogging thetool in boring. It will also be observed that the button 0 is so shapedas to tend to assist the shavings rather than obstruct them in recedingout of the hole being bored.

A large number-say twenty or more-01? different sizes of thecutter-heads C, all,how-

ever, having the same'internal shape and di-,

ameter, may be interchangeably used on the same stem A, the shoulders gand q always preventing any tendency in the tapering stem when used inboring to become'unduly tightened by wedging in the head; and thus Ipractically provide as many different bits as may be adapted for use onthe one stem, thereby affording to myimproved tool the attributes ofeconomy hereinbefore referred to.

To gage the depth of penetration of the tool, I provide on the stem agage D, adjust able for any depth to be bored in proportion to thelength of the stem. As shown, the gage comprises a skeleton skirt 'm,terminating at its lower end in a ring m, much greater in diameter thanthe stem A, and converging toward its opposite end into acircumferentially-grooved collar m which loosely fits aboutthestem; andZ is an annular head surrounding the stem and carrying a set-screw Z, bywhich to fasten it thereon at any point to which it may be moved, thehead being provided with a depending flange 1*, having aninward-extending lipl and reaching only part way about the annular head,whereby it may be engaged with the collar m by inserting the lip Z intothe groove thereof, when the whole may he slipped on the stem (as fromits upper end) and up or down thereon to the desired point, at which thegage may be fastened by suitably turning the set-screw Z.

What I claim as new, and desire to secure by Letters Patent, is-

1. A cutter-head for a bit provided with an external spiral ribterminating at its lower end in a cutting-edge i), an outercutting-point w and an inner cutting-edge v on the lower end of thehead, and an inner cutting-point w on an arc described on said lower endof the head, said cutting-edge '1) extending in a line tangential to thecircle on which said arc is described, substantially as and for thepurpose set forth.

2. A cutter-headfor a bit separable from and attachable on the stem ofthe tool and comprising a hollow head adapted to fit about and befastened on said stem, the head being provided with an external spiralrib terminating at its lower end in a cutting-edge and having an outercutting point, and an inner cutting-edge and an inner cutting-point onthe lower end of the head, substantially as described.

3. A bit comprising. a stem A provided with fastening meansB,acutter-head separable from and attachable on the stem and comprisinga hollow head provided with a slot 0 at which it is engaged by saidfastening means, the head having an external spiral rib n andterminating at its lower end in a cutting-edge 2; and having an outercutting-point w, and an inner cutting-edge 'v' and an innercutting-point w on the lower end of the head, substantially asdescribed.

4. In combination with a bit, a gage D adjnstably fastened upon the bitstem and comprising a skirt-portion m terminating at one end in a ring mand at its opposite end in a grooved collar m immediately and looselysurrounding the stem of the bit, and an annular head Z provided with aset-screw Z and with a flange Z having a lip Z to enter and engage thecollar at its groove, substantially as described.

FRANK W. NELSON.

In presence of M. J. FROST, J. H. LEE.

ICE

